This is the "worst-selling Microsoft product of all time" - and there's a good reason you've probably never heard of it

Microsoft Mach 20.

• The Mach 20 tried to bridge the gap between generations of PCs - but instead achieved near-total obscurity
• Only 11 units of OS/2 for Mach 20 ever reached customers
• Eight users who bought OS/2 for Mach 20 quickly returned it, disappointed

In the history of Microsoft’s successes, from Windows to its expansive suite of office software, lies an almost forgotten misstep which stands as a lesson in technological timing.